The present invention relates to a disc drive microactuator, and more particularly to improved spacing methods for use in a magnetic microactuator utilizing a vertical magnetic circuit contained on a substrate and a coil structure to provide microactuation force.
The density of concentric data tracks on magnetic discs continues to increase (that is, the size of data tracks and radial spacing between data tracks are decreasing), requiring more precise radial positioning of the head. Conventionally, head positioning is accomplished by operating an actuator arm with a large-scale actuation motor, such as a voice coil motor, to radially position a head on a flexure at the end of the actuator arm. The large-scale motor lacks sufficient resolution to effectively accommodate high track-density discs. Thus, a high resolution head positioning mechanism, or microactuator, is necessary to accommodate the more densely spaced tracks.
One promising approach for high resolution head positioning involves employing a high resolution microactuator in addition to the conventional lower resolution actuator motor, thereby effecting head positioning through dual-stage actuation. Various microactuator designs have been considered to accomplish high resolution head positioning. One design involves inserting a silicon-based thin film structure between the suspension and the slider in a disc drive assembly. A major technical challenge in implementing such a microactuator is to provide sufficiently large actuation force to overcome spring bias forces to drive the head at a speed high enough to accommodate the required bandwidth. Such a design must be realized in a relatively small wafer area, to keep costs reasonable and to allow easy integration into the disc drive design.
Therefore, there is a need in the art for a microactuator design providing large actuation force with reasonable power consumption and within a reasonable wafer area to microposition a transducing head at a speed that accommodates the high bandwidth required by high performance disc drives. Designs for achieving this goal are disclosed in U.S. application Ser. No. 09/315,006, filed May 19, 1999 for xe2x80x9cMagnetic Microactuatorxe2x80x9d by P. Crane, W. Bonin and B. Zhang, and in U.S. application Ser. No. 09/490,421 filed Jan. 24, 2000 for xe2x80x9cCoil Structures For Magnetic Microactuatorxe2x80x9d by P. Crane, W. Bonin and Z. Boutaghou, both of which are hereby incorporated by reference. Additional improvements to such a design are desirable to further advance the state of the art.
The present invention is an improved standoff design for a disc drive system employing a microactuator. The disc drive system includes a recording disc rotatable about an axis, a slider carrying a transducing head for transducing data with the disc, and a dual-stage actuation assembly supporting the slider for positioning the transducing head adjacent a selected radial track of the disc. The dual-stage actuation assembly includes a coarsely movable support structure and a microactuator. The microactuator includes a microactuator frame attached to the support structure which includes a stator and a rotor. The rotor is operatively attached to the slider and is movable with respect to the stator in a first horizontal plane parallel to the surface of the disc. A magnetic circuit is arranged to move the microactuator rotor and the slider in the first horizontal plane generally parallel to the surface of the disc, the circuit being partially formed on the microactuator frame and partially formed on the support structure. A plurality of standoffs are provided on the microactuator frame to precisely space the microactuator frame from the support structure. The standoffs are designed to control the flow of bonding agent to direct overflow in a predefined path that will not damage the microactuator, so that a consistent, precise spacing is achievable between the microactuator frame and the support structure.